1. The Origen of Species
Ch 24

2. Macroevolution
Evolution above the species level that produces novelties like vertebrae or feathers and contributes to speciation
Speciation- the process by which new species arise
Species: capable of reproducing
and making fertile offspring

3. Reproductive Isolation
Prevents different species from making fertile offspring.
May be “prezygotic” or “postzygotic”

4. Prezygotic barriers 1. Habitat isolation 2. Behavioral Isolation
3. Temporal(time) isolation
4. Mechanical isolation
5. Gametic isolation

5. Postzygotic barriers
1. Reduced hybrid viability- zygote doesn’t develop
2. Reduced hybrid fertility- offspring is sterile
3. Hybrid breakdown- fertile hybrids mate but their offspring are weak/sterile

7. Allopatric Speciation
“Different country” speciation due to geographic separation
Mountains forming, rivers separating, continental drift,etc

9. Sympatric Speciation “Same country” speciation-
Some barrier prevents mating
(Temporal, behavioral…)
Common in plants that easily
become polyploid instead of
diploid
--may result from Habitat
differentiation and
sexual selection

10. Adaptive radiation (divergent evolution)
-many species arise from a common ancestor which moved into a new area or niche

12. Rates of Speciation Gradualism- gradual accumulation of adaptations
Punctuated equilibrium- stable periods with occasional bursts of rapid changes in the fossil record

13. Evolution of Genes that Control Development
“Evo-devo” is the branch of study where evolution and developmental biology meet. -Slight changes can make major differences in morphology difference between species.

14. Homeotic Genes
Master control genes that determine the location and organization of body parts
Hox genes determine positional information in animal embryos that prompt cells to develop structures in a particular place
Changes can create drastic morphological effects